We determined the molecular weight and some properties of multiple forms of phenol oxidase from tea leaves and four other perennial plants. It was shown that multiple high and low molecular forms of phenol oxidase differed in substrate specificity. Low molecular forms of the enzyme mostly demonstrated hydroxylase activity, while high molecular forms showed catechol oxidase activity. It was revealed that the withering stage of black tea production is accompanied by the formation of only high molecular forms of phenol oxidase, which possess catechol oxidase activity crucial for the procurement of oxidative reactions and the quality of the product.

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Stabilities of phenol oxidase and peroxidase from tea plant ( Camellia sinensis L.) clone Kolkhida leaves, apple ( Mallus domestica L.) cultivar Kekhura fruits, walnut ( Juglans regia L.) green pericarp, and horseradish ( Armoracia lapathifolia Gilib) roots were studied using different storage temperature modes and storage duration. It was demonstrated that both enzymes retained residual activities ( ~10% ) upon 20-min incubation at 80 ° C. Phenol oxidases from tea, walnut, and especially apple, as well as tea peroxidase, were stable during storage. A technology for the treatment of plant oxidases was proposed, based on the use of a natural inhibitor of phenol oxidase and peroxidase, isolated from tea leaves, which solves the problem of residual activities of these enzymes that arises during pasteurization and storage of beverages and juices. It was demonstrated that browning of apple juice during pasteurization and beer turbidity during storage could be efficiently prevented using the natural inhibitor of these enzymes.

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